What practice involves colluding with other firms to control prices?

Price fixing is a practice where businesses collaborate to set prices at a certain level, rather than allowing market forces to dictate those prices. This collusion can occur in several ways, such as agreeing to sell products or services at a specific price or establishing a standard pricing policy that all participating firms adhere to. The primary goal of price fixing is to control or manipulate the market, often leading to higher prices for consumers and reduced competition.

In contrast, deceptive advertising refers to misleading marketing practices that may misrepresent the truth about a product or service, which does not involve collusion. Loss leader pricing is a strategy where a product is sold at a loss to attract customers, aiming to increase traffic and sales of other profitable items. Price discrimination involves charging different prices to different customers for the same product or service, typically based on willingness to pay, and is not inherently a collusive practice. Thus, the emphasis on collusion and market control clearly characterizes price fixing as the correct answer in this context.